Continuous method of manufacturing articles from foamed thermoplastic material

Claim 1

A continuous method of manufacturing articles from a thermoplastic polymeric resin strip, comprising causing a foamable thermoplastic polymeric resin heated to a plastic state and mixed with a blowing agent under pressure to flow along radials of a laterally diverging die passageway to a die orifice, continuously extruding and feeding a thin, narrow strip of said resin from said die orifice at a feed rate at least of the order of 40 feet per minute and expanding said resin to form a foam with a low density of no more than about 3 pounds per cubic foot, continuously spreading the extrudate laterally as the extrudate is fed from said die orifice and while the extrudate is expanding, to prevent the formation of wrinkles, thereby to form an expanded extrudate strip of the order of 0.020 to 0.300 inch thick and a maximum of about 18 inches wide, and thermoforming a series of individual articles from the spread extrudate to a depth in orthogonal planes of at least of the order of threeeighths of an inch by utilization of the heat of extrusion as the extrudate is continuously fed from said die, said forming being accomplished close enough to said die, and said extrudate being fed rapidly enough to permit such forming.